tests: remove explicit tmpdir deletions

These are no longer necessary.

Library/Homebrew/test/audit_test.rb

@@ -10,11 +10,6 @@ class FormulaTextTests < Homebrew::TestCase
     @dir = mktmpdir
   end
 
-  def teardown
-    FileUtils.rm_rf @dir
-    super
-  end
-
   def formula_text(name, body = nil, options = {})
     path = Pathname.new "#{@dir}/#{name}.rb"
     path.open("w") do |f|
@@ -64,11 +59,6 @@ class FormulaAuditorTests < Homebrew::TestCase
     @dir = mktmpdir
   end
 
-  def teardown
-    FileUtils.rm_rf @dir
-    super
-  end
-
   def formula_auditor(name, text, options = {})
     path = Pathname.new "#{@dir}/#{name}.rb"
     path.open("w") do |f|

Library/Homebrew/test/language_python_test.rb

@@ -15,11 +15,6 @@ class LanguagePythonTests < Homebrew::TestCase
     @venv = Language::Python::Virtualenv::Virtualenv.new(@formula, @dir, "python")
   end
 
-  def teardown
-    FileUtils.rm_rf @dir
-    super
-  end
-
   def test_virtualenv_creation
     @formula.expects(:resource).with("homebrew-virtualenv").returns(
       mock("resource", stage: true)

Library/Homebrew/test/pathname_test.rb

@@ -13,12 +13,6 @@ module PathnameTestExtension
     @file = @src/"foo"
     @dir  = @src/"bar"
   end
-
-  def teardown
-    rmtree(@src)
-    rmtree(@dst)
-    super
-  end
 end
 
 class PathnameTests < Homebrew::TestCase

Library/Homebrew/test/sandbox_test.rb

@@ -10,11 +10,6 @@ class SandboxTest < Homebrew::TestCase
     @file = @dir/"foo"
   end
 
-  def teardown
-    @dir.rmtree
-    super
-  end
-
   def test_formula?
     f = formula { url "foo-1.0" }
     f2 = formula { url "bar-1.0" }

Library/Homebrew/test/utils_test.rb

@@ -11,7 +11,6 @@ class UtilTests < Homebrew::TestCase
   end
 
   def teardown
-    @dir.rmtree
     ENV.replace @env
     super
   end